Electronic communications system

ABSTRACT

An electronic communication system for a vehicle, including a base station which is accommodated in the vehicle and at least one portable data carrier which is arranged to exchange data signals with the base station. A first coupling link is formed at least partly by the body of a user, whose skin is not required to be in physical contact with the data carrier, so that the body of the user contactlessly conducts displacement currents from the data carrier without contacting the data carrier. This permits the user to unlock a car door, or trunk, and/or start the vehicle, without using a key or having to touch a remote control device. The data carrier can be located in a briefcase and/or purse, and the ability to access the vehicle is not comprised even though there is no physical contact between the user and the data carrier.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an electronic communication system for avehicle, including a base station which is accommodated in the vehicleand at least one portable data carrier which is arranged to exchangedata signals with the base station.

2. Description of the Related Art

Communication systems of this kind serve notably for controlling theentry to the vehicle. Systems of the kind set forth are known as“keyless central locking systems” or “keyless go-inhibit systems”. Sucha system is described in the article “Türsteher ohne Bodyguard-Format”by Dr. Stephan Schmitz and Jasek Kruppa, published in the magazine“Elektronik”, Vol. 22, 1998, pp. 148 to 156.

The cited publication discloses a keyless central locking system for usein vehicles which includes the following components:

-   a transponder which can be embedded in a chip card or in a key grip    and may be provided with an antenna coil, a battery, a UHF    transmitter and pushbuttons,-   an LF antenna in the mirror on the driver's door,-   an UHF receiver in the vehicle which is activated as soon as it    receives (deliberately triggered by the user) an appropriate UHF    sequence from the transponder,-   a mechanical switch in the door handle for activating a passive    entry system, including an additional pushbutton for initiating the    locking procedure, the base station or the door module and a control    device.    The transponder transmits data signals to the vehicle via a UHF    link, whereas the transmission from the vehicle to the transponder    always takes place via an LF signal of a frequency of 125 kHz. If    desired, the transmission from the transponder to a vehicle can also    be realized by means of such an LF signal.

A keyless locking system of this kind is capable of simplifying theopening of a vehicle to some extent in comparison with the use of amechanical door key. However, such simplification is limited by the factthat the user must still find and operate the transponder as before.Thus, the problem remains that the transponder must always be carried ina pocket or the like and that it must be retrieved therefrom in order tooperate it. It is also to be noted that even this minor advantage is notachieved for the go-inhibit function, i.e. for the starting of thevehicle.

SUMMARY OF THE INVENTION

It is an object of the invention to provide an electronic communicationsystem which allows for very simple operation in a wide variety ofcircumstances.

This object is achieved in an electronic communication system of thekind set forth in that

-   the data carrier includes a first and a second electrode as well as    a first data signal processing circuit which is arranged to receive    and/or transmit the data signals from and to the base station,    respectively, the data signals being formed by a voltage between the    first and the second electrode,-   the base station includes at least a third and a fourth electrode as    well as a second data signal processing circuit which is arranged to    receive and/or transmit the data signals from and to the data    carrier (carriers), respectively, the data signals being formed by a    voltage between the third and the fourth electrode,-   during operation, the second and the third electrode are coupled to    one another via a first coupling link for the transmission of the    data signals,-   during operation the first electrode is coupled to electrical ground    of the vehicle via a second coupling link for the transmission of    the data signals,-   the fourth electrode is electrically connected to electrical ground    of the vehicle, and-   the first and the second coupling link include at least a respective    capacitive connection via an electrical field.

The communication system according to the invention enables not onlyvery simple operation but a very high degree of reliability in a widevariety of circumstances, notably a high degree of protection againstunauthorized entry. This is achieved notably in that the coupling linksconstructed in conformity with the invention have a range which islimited to the minimum value required for user-friendly operation, sothat unauthorized entry by non-authorized third parties is precluded.This is achieved notably by the capacitive connections. Moreover, thecommunication system according to the invention is constructed to bevariable in such a manner that it can be simply used for a variety ofapplications and types of operation. Specifically, it makes nodifference whether operation takes place outside or inside the vehicle.

The first coupling link in a preferred embodiment of the communicationsystem according to the invention is formed at least partly by the bodyof a user which conducts displacement currents. This offers theadvantage that a coupling link of this kind can be implemented so as tobe very well protected against tapping. Moreover, this constitutes aparticularly simple implementation and operation of the communicationsystem. The second coupling link in a further embodiment of theinvention is formed at least partly by the ground. In the case of a landvehicle this is the ground or the pavement. In the case of a watervehicle, the second coupling link may also be formed at least partly bythe water. This embodiment also simplifies the communication system;more specifically, the ground will invariably form a link between thevehicle and a user who is outside the vehicle, irrespective of theposition of the vehicle.

Preferably, the communication system according to the invention includesat least an additional data and/or energy transmission link whichinvolves an essentially magnetic coupling between the data carrier (datacarriers) and the base station. This additional facility creates abackup system which satisfies only less severe requirements in respectof operation and reliability, but offers an emergency solution in thecase of failure of the described devices of the communication systemaccording to the invention.

If desired, coupling by way of electromagnetic waves in the UHF range orby way of infrared light can be used instead of the magnetic coupling.

The invention thus offers an electronic communication system which isbased on active, capacitively coupled data carriers and electricalfields preferably conducted inside the body of a user. An emergencysystem which is preferably realized with inductive coupling can also beintegrated. This communication system enables operation of a vehicle insuch a manner that the user is granted entry to the vehicle withoutseparate activation of a key or a comparable entry control system, butmerely by activation of a door handle; moreover, the user can equallysimply put the vehicle into operation, for example by actuating astarter button. The electronic communication system according to theinvention monitors the entry authorization and takes the necessaryprotective measures against unauthorized actuations. In order to achievethis object, the user need not perform any additional operations suchas, for example, actuation of a remote transmitter or a mechanical key.The authorized user instead is fully automatically recognized andauthorized by the communication system according to the invention. Theuser carries the associated, portable data carrier in or under his orher clothing or in a purse or the like. The electrodes may be formedsimply as proximity fields or touch fields in the actuation elements ofthe vehicle, for example the door handle or an ignition button. Thearrangement of such electrodes in the communication system according tothe invention offers an as high as possible degree of user comfort andreliability, notably protection against unauthorized access.

It is to be noted that the document WO 96/36134 discloses a wirelesssystem which includes a transmitter and a receiver which are coupled viaa user and the ground potential of a room. The transmitter generateslow-frequency signals of low power which, due to capacitive coupling,flow through the body of the user as displacement currents. Thedistributed ground potential of the room constitutes the return path forthe current.

It is also to be noted that EP 0 843 425 A2 discloses an electroniccommunication apparatus which utilizes the human body as a transmissionmedium. This apparatus serves to encrypt and transmit data from atransmitter, preferably constructed as a card, to a receiver which ispreferably included in a base station. The transmitter includes agenerator for an electrical field, a data encryption device which isactivated by modulation of the electrical field, and electrodes forcoupling the electrical field through the human body. The receiverincludes electrodes which are in physical contact with or are arrangedvery near to a part of the human body so as to detect an electricalfield transmitted by the body. A demodulator in the receiver extractsthe data from the modulated electrical field. It is also indicated thata receiver electrode may be arranged in a metallic door handle of avehicle.

The doors should thus be automatically unlocked when the bearer of anauthorized card, i.e. an authorized transmitter, touches the door handleby hand. Touching the door handle without pulling it over a given periodof time, for example 15 seconds, is intended to lock all doors.

Thus, from the cited documents it is known in principle to useelectrical fields for data transmission by way of displacement currentsthrough the human body. However, these documents do not reveal how sucha system should be implemented so as to achieve the cited objects.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are shown in the drawing and will bedescribed in detail hereinafter. Corresponding elements in the drawingsare denoted by corresponding references; in the drawings:

FIG. 1 is a diagrammatic representation of a first embodiment of theelectronic communication system according to the invention,

FIG. 2 shows diagrammatically a first mode of operation of thecommunication system of FIG. 1,

FIG. 3 shows diagrammatically a second mode of operation of thecommunication system shown in FIG. 1,

FIG. 4 shows diagrammatically a third mode of operation of thecommunication system shown in FIG. 1,

FIG. 5 shows diagrammatically a fourth mode of operation of thecommunication system shown in FIG. 1, and

FIG. 6 shows a block diagram of an embodiment of a base station and adata carrier of the communication system shown in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows an embodiment of an electronic communication systemaccording to the invention in which the exchange of data signals cantake place at least partly via the body of a user and at the same time,or optionally, via the ground. Moreover, this embodiment of thecommunication system according to the invention can also be implementedwithout incorporating these two transmission media.

In FIG. 1, illustrating the principle and at the same time a first modeof operation of the embodiment, the electronic communication systemincludes a base station 1, installed in a vehicle, and at least oneportable data carrier 2 which is arranged to exchange data signals withthe base station 1. The data carrier 2 includes a first electrode 3 anda second electrode 4. The data carrier 2 is preferably constructed so asto be essentially flat, for example in the form of a card. Theelectrodes 3, 4 then cover at least partly the opposite principalsurfaces of the card. A first data signal processing circuit 5, arrangedto receive and/or transmit the data signals from and to the base station1, respectively, is included in the data carrier 2. The data signals areformed by a voltage between the first electrode 3 and the secondelectrode 4; the data carrier 2 includes appropriate connections betweenthe first data signal processing circuit 5 and the electrodes 3, 4.

The base station 1 includes at least a third electrode 6 and a fourthelectrode 7 as well as a second data signal processing circuit 8. Thesecond data signal processing circuit 8 is arranged to receive and/ortransmit the data signals from and to the data carrier 2, respectively.The data signals are again formed by a voltage between the thirdelectrode 6 and the fourth electrode 7; appropriate connections areprovided between the second data signal processing circuit 8 and thethird electrode 6 and the fourth electrode 7.

During operation of the present embodiment of the communication systemaccording to the invention, the second electrode 4 and the thirdelectrode 6 are coupled to one another via a first coupling link for thetransmission of the data signals. In conformity with FIG. 1, the firstcoupling link includes a first capacitive connection 9 via an electricalfield between the second electrode 4 and the body of a user 10. A secondcapacitive connection 11 in the first coupling link is formed via anelectrical field between the body of the user 10, in this case notablythe users hand, and the third electrode 6. Moreover, in conformity withFIG. 1 the first coupling link is formed at least partly by the body ofthe user 10 carrying displacement currents 12. The first and the secondcapacitive connection 9, 11 and the body of the user 10 with thedisplacement currents 12 conducted therein are connected in series so asto form the first coupling link.

Furthermore, in FIG. 1 the fourth electrode 7 is electrically connectedto electrical ground 13 of the vehicle. During operation of thecommunication system shown, between electrical ground 13 and the firstelectrode 3 a coupling exists via a second coupling link for thetransmission of the data signals. In the simplest representation of FIG.1, the second coupling link includes a third capacitive connection 14via an electrical field between the first electrode 3 and ground 13.

The following Figures illustrate variations and different modes ofoperation of the embodiment of the communication system shown in FIG. 1.The base station 1 may be connected to several electrodes, each of whichitself performs the function of the third electrode 6. This means thatthe first coupling link may extend via each of these electrodes asdesired. Preferably, these electrodes for the various operation purposesare arranged in different locations outside and inside the vehicle.

FIG. 2 shows an embodiment of the communication system according to theinvention where the user 10 is outside the vehicle 20. Such aconfiguration of the communication system according to the inventionoccurs notably in controlling the entry to the vehicle, i.e. for thelocking and authorized unlocking of the doors or also a trunk lid. Tothis end, a third electrode 60 is provided in a first mounting locationon the door handle or on the actuation member for the trunk lid on theexterior of the vehicle. The connections and notably the coupling linksfor the transmission of the data signals are then formed as follows. Thefirst coupling link again includes the first capacitive connection 9between the second electrode 4 of the data carrier 2 and the body of theuser 10. Via displacement currents 12 within the body of the user 10,the data signals are conducted to the hand of the user 10. The secondcapacitive connection 11 extends from the hand of the user 10 to thethird electrode 60 on the door handle. The second coupling link as shownin FIG. 2 includes first of all the third capacitive connection 14between the first electrode 3 of the data carrier 2 and the ground, i.e.the ground or the pavement on which the vehicle 20 rests. The ground isdenoted by the reference 16. A fourth capacitive connection 15 existsbetween the ground 16 and the electrical ground 13 of the vehicle 20.The connection in the ground 16 preferably is realized again viadisplacement currents. The two capacitive connections 14, 15 and theground, or the displacement currents flowing therein, are againconnected in series in the second coupling link.

FIG. 2 shows not only the connection between the third electrode 60 andthe base station 1, but also a further connection 61 which extends to afurther third electrode. Instead of the further connection 61, however,a plurality of such further connections may be provided, depending onthe number of third electrodes provided in or on the vehicle 20.

FIG. 3 shows a version of the embodiment of the communication systemaccording to the invention where the user 10 sits in the vehicle. Thisversion occurs notably when an authorized starting operation is to becarried out for the engine of the vehicle 20. In this version the firstcoupling link again consists of the first capacitive connection 9 andthe second capacitive connection 11 as well as the displacement currents12 in the body of the user 10. As opposed to the general illustration ofFIG. 1, FIG. 3 shows the first capacitive connection 9 in a manner so asto symbolize a particularly close proximity between the user 10 and thedata carrier 2, i.e. a particularly tight capacitive coupling. As willbe demonstrated, however, this is not absolutely necessary for theimplementation of the communication system according to the invention.The second capacitive connection 11 leads to a third electrode 62 inFIG. 3, which electrode is mounted in a second location which ispreferably situated on the dashboard, notably at the area of anactuation element for the starter of the engine of the vehicle. Thethird electrode 62 is advantageously combined with such an actuationelement for the ignition. Upon actuation by the hand of the user 10, theauthorization check is then automatically performed and the engine ofthe vehicle 20 will be started in the case of a positive result.

In the embodiment shown in FIG. 3 the second coupling link consists ofthe third capacitive connection 14 between the first electrode 3 andground 13 of the vehicle 20. Therefrom a direct, electrically conductiveconnection extends to the base station 1 via the fourth electrode 7.

Because the third electrode 60 in the location “door-handle” as well asthe third electrode 62 in the location “actuation member for ignition”is connected to the base station 1, the communication system thus formedcan be very simply and flexibly used for controlling the entry to thevehicle 20 as well as for authorizing the starting operation. Thecommunication system can thus be used for passive entry control as wellas for passive motion control, i.e. as a go inhibitor. Operation is verysimple, because the user 10 need only touch the door handle and theactuation member for the ignition. Separate actuation, for example bymeans of a key, is dispensed with. As a result of the mounting of thethird electrodes 60 and 62 and the carrying of the data carrier 2, theoperations required for the data exchange are automatically performed,i.e. the transmission of the necessary data signals for theauthorization checks, without intervention by the user 10. Anon-authorized user is thus reliably prevented from carrying out thesefunctions. Due to the capacitive coupling, moreover, the range of thedata transmission in the communication system according to the inventionis limited to the bare minimum, so that a non-authorized third partycannot tap the exchange of data signals between the data carrier 2 andthe base station 1.

The data carrier 2 in the embodiments shown is preferably represented asa card-like element. However, the data carrier 2 may also be formed as akey ring, a wrist watch, a watchband or a part thereof. Furthermore, anyother construction is also feasible, for example as a clothing label orthe like.

The communication system according to the invention also enablesidentification of the position of the user 10 without requiringadditional means. This identification is very simply possible via theconfiguration of the coupling links via the various mounting locationsof the third electrodes 60, 62. This identification also serves for theoperating reliability of the communication system. For example, shouldthe user 10 with the data carrier 2 be present outside the vehicle 20,it can be prevented with certainty that a second, non-authorized person,for example a child, in the vehicle 20 can perform successful actuationof the control elements of the vehicle 20 in as far as these elementsare taken up in the entry control by the communication system accordingto the invention. It is notably impossible for such a person to actuatethe actuation element for the ignition. In another case the inventioncan also simply prevent the vehicle 20 from being locked from theoutside by a non-authorized user for as long as the authorized user 10sits in the vehicle.

The identification as to which of the third electrodes 60, 62 is totrigger an actuation operation can be realized simply by detecting thatelectrode via which the data transmission is initiated, i.e. detectingwhere the capacitive connection is established. Moreover, a logiccombination can be formed with said actuation elements for the doorhandle or the ignition, supplying the base station 1 with correspondinginformation. As a result of such a logic combination, conversely, allthird electrodes not selected at the relevant instant can bedeactivated. The operator of the user 10 can thus always be exactlydefined. In order to detect via which third electrode the data exchangeshould take place, the base station 1 can also cyclically interrogateall third electrodes for the presence of a data signal, i.e. anelectrical field or a capacitive connection. In the case of a positiveinterrogation result, the data exchange for the entry or authorizationcheck is then automatically started.

The third electrodes 60, 62 are preferably constructed as actuationmembers which are electrically insulated from the vehicle 20. If this isnot desirable or impossible from a construction point of view, suchactuation members can be provided with electrically insulated electrodepads. For example, such electrode pads can be mounted on or underneaththe door handles. For example, mounting underneath the door handle atthe same time offers protection against the weather.

Mounting such electrodes in the windows of the vehicle 20 or within arearview mirror may also be advantageous.

As opposed to these embodiments which are advantageous for controllingthe entry to the vehicle 20, the third go-inhibit electrode 62 insidethe vehicle 20 is mounted preferably directly on the actuation memberfor the ignition, for example on the surface of a pushbutton switch. Aconstruction in the form of a key-like switch which is to be actuated bya turning motion is also possible; the third electrode 62 can then bearranged on the surface of the grip of such a switch. Such aconstruction could be desirable in order to preserve for the user 10 thecustomary actuation motion for conventionally equipped vehicles.

Alternatively, the third electrode 62 may be formed by the steeringwheel or a part thereof. A combination with an appropriately constructedactuation member for the ignition is also possible. The startingprocedure for the vehicle is then triggered by touching the steeringwheel and at the same time actuating the ignition. The actuation of apedal or the combined actuation of several pedals can also be used totrigger the starting procedure in combination with the touching of thethird electrode 62. Moreover, the reliability of exact identification ofthe position of the user 10 can be enhanced by providing additionalthird electrodes on at least one of the pedals. In that case the entrytest is performed twice in succession, i.e. the first time via theactuation member for the ignition and the second time via the pedals, oralso vice versa.

The foregoing considerations also hold to the same extent when the datacarrier 2 is carried close to the body of the user 10, so that the firstcapacitive connection 9 is always very active. In that case there are nodifferences in the effectiveness of the communication system in relationto the entry control function and the go-inhibit function.

These circumstances change when for various reasons the data carrier 2is not carried close to the body of the user 10. For example, oftenthere are no suitable pockets in women's clothing. The communicationsystem according to the invention is conceived to be such that the datacarrier can also be carried along in a handbag, a briefcase or the like,without affecting the effectiveness. However, such a briefcase shouldnot exert a strong electrically shielding effect, for example like analuminium case. The electrical field strengths, notably for the firstcapacitive connection 9, therefore, are proportioned so that error-freedata transmission is ensured also when the data carrier is carried in ahandbag or similar container comparatively close to the body.

Such circumstances are shown, by way of example, in FIG. 4. In this casethe user 10 carries the data carrier 2 in a briefcase 21. The firstcapacitive connection 9 then extends from the second electrode 4 to thebody of the user 10 and continues therein via the displacement currents12.

In the configuration shown in FIG. 4, however, in addition to anincreased distance between the second electrode 4 and the body of theuser 10 there may also occur parasitic displacement currents 17 whichthen flow through the legs of the user 10 to the ground 16 andestablish, via said ground, a connection to the third capacitiveconnection 14. The members of the data carrier 2, notably the first datasignal processing circuit 5, should be proportioned to ensure that theseparasitic displacement currents will not endanger correct transmissionof the data signals.

A modified configuration of the communication system according to theinvention, however, arises when a data carrier which is not carrieddirectly on the body of the user 10 is placed in the vehicle 20. It maythen occur that the physical distance between the data carrier, notablythe second electrode 4 thereof, and the body of the user 10 becomes toolarge so as to achieve correct data transmission. FIG. 5 shows suchcircumstances on the basis of a data carrier 2 which is stored in abriefcase 21 placed on a seat 22 of the vehicle. In that case datatransmission no longer takes place via the body of the user 10. Insteadfurther third electrodes are mounted in further locations in thevehicle. FIG. 5 shows, by way of example, a third electrode 63 mountedat the third location in the vehicle seat 22. The third electrode 63 maybe formed by a metallic mesh or metal wires in the seats or by themetallic seat springs, but a seat heating by means of electrical heatingwires can also be used for this purpose. The third electrode 63 isconnected to the base station 1 in the same way as the third electrodes6, 60 and 62 and can also be identified in the same way via thisconnection. The first coupling link in this configuration includes onlythe first capacitive connection 9; the second coupling link onlyconsists of the third capacitive connection 14. The communication systemaccording to the invention enables very reliable and simple datatransmission also in this mode of operation.

FIG. 6 shows an embodiment of the basic circuit construction of the datacarrier 2 and the base station 1. The first data signal processingcircuit 5 of the data carrier 2 in this embodiment includes a resonantcircuit which includes an inductance 23 and a capacitance 24 as well asa circuit 25 with a demodulator. The circuit 25 serves to demodulate andprocess received data signals. There is also provided a driver circuit26 which serves to transmit data signals. The inductance 23 and thecapacitance 24 form a series resonant circuit which is connected to thedriver circuit 26. Furthermore, the second electrode 4 and the circuit25 are connected to the junction of the inductance 23 and thecapacitance 24. The first electrode 3 is connected to the junction ofthe capacitance 24 and the driver circuit 26.

Similarly, the second data signal processing circuit 8 of the basestation includes an inductance 27, a capacitance 28, a circuit 29 with ademodulator, and a driver circuit 30. These elements are interconnectedin the same way as the corresponding elements of the data carrier 2. Thethird electrode is connected to the junction of the inductance 27 andthe capacitance 28 and the fourth electrode 7 is connected to thejunction of the capacitance 28 and the driver circuit 30. Whereas thefirst, the second, the third and the fourth electrode are cone anothervia the capacitive connections 9, 14, 15 in the described manner, anadditional coupling exists between the inductances 23 and 27, saidcoupling being denoted by the reference 31. The data carrier 1 and thebase station 2 can also exchange data signals via this additional,inductive coupling 31. In the receiving mode the driver circuits 26 and30 are short-circuited and the inductances 23 and 27 form parallelresonant circuits in conjunction with the associated capacitances 24 and28, respectively.

The described construction very simply allows for a communication systemwith capacitive connections in which an inductive connection isintegrated. Simple means thus enable communication at option via bothconnections. Because the inductive connection is preferably providedonly as an emergency connection, the physical dimensions of theassociated inductances may be small and the inductive coupling may beproportioned in such a manner that it is effective only over very smalldistances. This suffices for said emergency function and enhances thesecurity against tapping of the communication system.

The inductances for the inductive connection, also referred to asantenna coils, at the side of the base station may be provided in, forexample the rearview mirror of the vehicle or in the dashboard. Thecommunication system can then be operated via the capacitive connectionsas well as via the inductive connections from all desired locations.This enhances the reliability of the communication system according tothe invention via an emergency function which is available on all sides,notably also in the case of unfavorable weather conditions.

The communication system according to the invention is particularlyfailsafe in this sense, notably also in case the power supply for thefirst data signal processing circuit 5 of the data carrier 2 breaks downcompletely. The communication system according to the invention,moreover, can also be combined with UHF or infrared data connections.This not only enhances the operating reliability because of theavailability of additional emergency functions, but also enables veryuniversal use in existing systems utilizing such data connections.

1. An electronic communication system for a vehicle, including a basestation which is accommodated in the vehicle and at least one portabledata carrier which is arranged to exchange data signals with the basestation, wherein: the data carrier includes a first and a secondelectrode as well as a first data signal processing circuit which isarranged to receive and/or transmit the data signals from and to thebase station, respectively, the data signals being formed by a voltagebetween the first and the second electrode, the base station includes atleast a plurality of third electrodes and a forth electrode as well as asecond data signal processing circuit which is arranged to receiveand/or transmit the data signals from and to the data carrier(carriers), respectively, the data signals being formed by a voltagebetween the respective ones of the plurality of third and the forthelectrode, during operation the second and one of the plurality of thirdelectrodes are coupled to one another via a first coupling link for thetransmission of the data signals, during operation the first electrodeis coupled to electrical ground of the vehicle via a second couplinglink for the transmission of data signals, the fourth electrode iselectrically connected to electrical ground of the vehicle, and thefirst and second coupling links include at least a respective capacitiveconnection via an electrical field; wherein the first coupling link isformed at least partly by the body of the user, whose skin is notrequired to be in physical contact with the data carrier, so that thebody of the user contactlessly conducts displacement currents from thedata carrier without contacting the data carrier; and wherein the datacarrier and the base station have a magnetic backup coupling byinductance that does not require the body of the user for operation,wherein the each of the plurality of third electrodes correspond to apredetermined function of the vehicle, the first coupling link requiringthe second electrode to be in closer proximity with a first one of theplurality of third electrodes to actuate a first function of the vehiclethan with a second one of the plurality electrodes to actuate a secondfunction of the vehicle.
 2. An electronic communication system asclaimed in claim 1, characterized in that the second coupling link isformed at least partly by the ground.
 3. An electronic communicationsystem as claimed in claim 1, characterized in that it includes at leastan additional data and/or energy transmission link which involvesessentially magnetic coupling between the data carrier (data carriers)and the base station.
 4. An electronic communication system as claimedin claim 1, characterized in that it includes at least an additionaldata and/or energy transmission link which involves a coupling betweenthe data carrier (data carriers) and the base station which is formedessentially by electromagnetic waves in the UHF range.
 5. An electroniccommunication system as claimed in claim 1, characterized in that itincludes at least an additional data and/or energy transmission linkwhich involves a coupling between the data carrier (data carriers) andthe base station which is formed by infrared light.
 6. A data carrierfor an electronic communication system as claimed in claim
 1. 7. Anelectronic communication system as claimed in claim 1, characterized inthat the vehicle further includes a logic element that enables ordisables selected ones of the functions of the vehicle depending adetected position of the user.
 8. An electronic communication system fora vehicle, including a base station which is accommodated in the vehicleand at least one portable data carrier which is arranged to exchangeddata signals with the base station, wherein: the data carrier includes afirst and a second electrode as well as a first data signal processingcircuit which is arranged to receive and/or transmit the data signalsfrom and to the base station, respectively, the data signals beingformed by a voltage between the first and the second electrode, the basestation includes at least a plurality of third electrodes and a forthelectrode as well as a second data signal processing circuit which isarranged to receive and/or transmit the data signals from and to thedata carrier (carriers), respectively, the data signals being formed bya voltage between the respective ones of the plurality of third and theforth electrode, during operation the second and one of the plurality ofthird electrodes are coupled to one another via a first coupling linkfor the transmission of the data signals, during operation the firstelectrode is coupled to electrical ground of the vehicle via a secondcoupling link for the transmission of data signals, the fourth electrodeis electrically connected to electrical ground of the vehicle, and thefirst and second coupling links include at least a respective capacitiveconnection via an electrical field; wherein the first coupling link isformed at least partly by the body of the user, whose skin is notrequired to be in physical contact with the data carrier, so that thebody of the user contactlessly conducts displacement currents from thedata carrier without contacting the data carrier; and wherein the datacarrier and the base station have a magnetic backup coupling byinductance that does not require the body of the user for operation,wherein the each of the plurality of third electrodes correspond to apredetermined function of the vehicle, the first coupling link requiringthe second electrode to be in closer proximity with a first one of theplurality of third electrodes to actuate a first function of the vehiclethan with a second one of the plurality electrodes to actuate a secondfunction of the vehicle, characterized in that the first one of theplurality of electrodes corresponds to vehicle ignition, and the secondone of the plurality of electrodes corresponds to locking/unlockingdoors.
 9. An electronic communication system as claimed in claim 7,characterized in that the logic element disables vehicle ignition if thedetected position of the user is outside the vehicle.
 10. An electroniccommunication system as claimed in claim 8, characterized in that itincludes at least an additional data and/or energy transmission linkwhich involves essentially magnetic coupling between the data carrier(data carriers) and the base station.
 11. An electronic communicationsystem as claimed in claim 8, characterized in that it includes at leastan additional data and/or energy transmission link which involves acoupling between the data carrier (data carriers) and the base stationwhich is formed essentially by electromagnetic waves in the UHF range.12. An electronic communication system as claimed in claim 8,characterized in that it includes at least an additional data and/orenergy transmission link which involves a coupling between the datacarrier (data carriers) and the base station which is formed by infraredlight.
 13. A data carrier for an electronic communication system asclaimed in claim 8.